Method of atomization and delivery of highly viscous hydrocarbon fuels



Jan. 5, 1937. 2,066,703 METHOD OF ATOMIZATION AND DELIVERY OF HIGHLY v1scous HYDROCARBON FUELS T.,- J. STEPHENS r 2 Sheets-Sheet l I Filed Jan. 16, 1952 Thomas ms p n INVENTOR i ATTORNEY Jan. 5, 1937. T. J. STEPHENS METHOD OF ATOMIZA'IIION AND DELIVERY OF HIGHLY VISCOUS HYDROCARBON FUELS 2 Sheets-Sheet Filed Jan; 16, 1932 'Thomaa l-Sl'ephens INVENTOR 2w ATTORNEY Patented Jan. s, 1937 "UNITED STATES aooavos ATENT OFFICE METHOD OF ATOMIZATION AND'DELIVERY F LgIGHLY VISCOUS HYDROCARBON Thomas .l'. Stephens, Brooklyn, Y.

Application January 16, 1932, Serial No. 587,087

2 Claims. (01. its-117.5)

invention relates to improvements in the method of atomization and delivery of highly viscous hydrocarbon fuels preparatory to burning same.

5. In the practice of burning on the fundamental requirementfor ignition and combustion is that the oil be, by some means, divided into flne particles and, while in this condition, mixed with a combustion supporting medium, such as air. *The rapidity of ignition and completeness of combustion will be P rtional to the degree of fineness to which the oil has been divided. This subdivision of the oil into fine particles, and suspensio'nof the particles in atmosphere is called l .atomization".-

Up to the present eflorts to solve this probiemof burning fuel oil have taken on three diiferent phases: .First, atomization of the fuel by mechanical means in the presence of a stream of combustion supporting medium, preferably air, which is used essentially as a vehicle to carrytheatomized fuel into themes of combustion; second, atomization by introducing the fuel into a jet of steam of sumcient volume and velocity to bring about atomization of the fuel being fed and to utilize the steam jet as a vehicle by means of which the atomized fuel reaches the combustion area: and third, atomization of the fuel by feeding. the latter, in a highly liquid state,

- into a jet of air having a volume and velocity sufllcient to atomize the liquid fuel, the atomized fuel being carried within the-jet into the area of combustion.

Y As I shall point out hereinafter. each of these as methods has its inherent disadvantages as well as its points of merit, and it is the purpose of V the present invention to employ a method of and apparatus 'for bringing about the atomization and delivery of highly viscous fuel oil in 40 atomized state to a combustion chamber in a manner which will combine. the advantages of the above mentioned methods and at the same time avoid their disadvantages.

I The first of these methods depends for atomi- 4 6 zation of the fuel upon -mechanical elements moving at high rates of speed, which are dlfli-' cult ofmaintenance, and are therefore objectionable because of excessive first cost, as well as excessive maintenance cost coupled with nu- 50 merous diillculties encountered in stabilizing their peri'ormances. 4 Referring to the'second method, it will be observed that the atomization oi. viscous fuel by means of a steam jet-has the advantage of 3 high temperature at thepoint where atomization takes place, but unless the steam has been superheated and the oil preheated, condensation will occur at the point of atomization and the resultant water will be carried by the jet into the combustion area and will lower its tempera- 5 ure.

' This unfavorable lowering of temperature is added to by the fact that the atomized iuel'is being carried into the combustion area suspended in a volatile vehicle (steam) which does 10 not support combustion, but which because of its tendency to decompose in the presence of carbon at flame temperature, further lowers the temperature of the combustion area, requiring a secondary reaction for complete development 15 of the heat content of the fuel. Another no less important disadvantage pertinent to the use of steam for atomization is the excessive released from pressure its temperature is low- 30 ered in proportion to the drop in pressure. It

' extremely important to note that this lowering in temperature takes placeat the point of release in pressure, and thispoint is the point of-atomization (where pressure is translated into velocity). It istherefore at this point that a heated condition should exist and anything approaching a freezing temperature should be avoided by all means. Because release from pressure is a cooling process but nevertheless is re- 40 quired to produce velocity in the jet, and because the atomizing power of the jet is directly proportional to its velocity and volume, and so also,

is its cooling effect upon the oil,-the process falls. short of its purpose when applied to heavy oil, in that viscosity of the fuel, resisting atomization, increases directly as the power to atomize is increased.

The method, universally used to reduce viscosity in fuel oil is to increase the temperature 5 of the viscous oil prior to the attempt being made toatomize it.

If'also the temperature of the atomizing medium, namely steam or air, under pressure, be

raised independently of its pressure, sufliciently u high that when released from pressure, its temperature will still be substantially above that required to maintain the fuel in its highly liquid state, then two advantageous conditions contributing to perfect atomization and complete combustion of the atomized fuel in the combustion area will have been accomplished.

Briefly, the two conditions referred to are; first, establishment and maintenance of temperature conditions at the point of atomization; second, increase in the atomizing power of the jet. The first condition is thought to be obvious. The second condition is accounted for in the increase in volume of air when heated; i. e. upon raising the temperature of one cubic foot of air under five pounds of pressure to 510 Fahr. from an initial temperature of 60 Fahr. its volume will be doubled. As a result, two cubic feet of air at five pounds pressure instead of one cubic foot passes into the atomizing jet at the point of release in a given time interval. Hence, either the velocity or the volume of the jet may be doubled. In either case its atomizing power will be doubled. These two conditions, namely, maintenance of temperature at the point of atomization combined with increased atomizing power in a given quantity of atomizing medium result in a more perfect preparation of the fuel for complete combustion than can be attained in the absence of either of said conditions by a given expenditure of energy.

along paths in heat exchange relation imme-' diately prior to their atomizing conjunction; and I secure stability of this temperature relation by controlling the preheating influence by the temperature of the atomizing medium at a point beyond the paths in heat exchange relation. This temperature control can be accomplished, but in a less satisfactory degree from a point in the path of the heated medium between the heater and the heat exchanger.

One embodiment of myinvention is described in the following specification and illustratively exemplified in the accompanying drawings and all embodiments are defined in the appended claims.

Figure 1 is a view partly in section on an oil burning installation carrying out the method of the present invention.

Figure 2 is a substantially longitudinal sectional view of a fuel heating unit and'its connection with an atomizer; and

Figure 3 is a diagrammatic view of an installation embodying means for using steam.

Referring to the drawings and particularly to -Figure 1, l0 denotes a combination oil and air .its air under pressure through a pipe line 22 and a helical coil 23 of a heater 24. A heating element 25 is disposed beneath the coils 23 and in the present disclosure it is a gas burner supplied with gas from a line 26 in which is disposed a throttle valve 21. The valve is controlled by a temperature actuated llqjfld in tube 23 and bulb 29, the latter being placed in the heated air line leading to the atomizer as hereinafter described. The heater 24 comprises in addition to the coil 23 an upright cylindrical casing 30 embracing the coil, the cell having its intake at the upper end of the casin and its delivery at the lower end adjacent the heat generator 25.

The air under pressure and heated in the coil 23 to a degree controlled in response to its temperature at a later stage, enters directly into a central air path of an oil or fuel heating unit 2| which comprisesa laterally disposed tubular metal casing 31, the bore of which is interiorly threaded at its opposite ends, the casing being further provided with the interiorly threaded radially disposed ports 20 and 20 adjacent opposite ends respectively. These ports communicate with theinterior of the bore-of the casing and allow the entrance and exit of the fuelas it passes or flows through the casing. Arranged coaxially of the casing 3| is a tube 32, of relatively smaller diameter than the casing bore and provided with an annular collar 33 at each end. Each collar is beveled outwardly from its bore to form a union seat 34 against which the conically shaped end of a bushing 35 is disposed, the joint comprising a union, the threaded member of which screws into the threaded end of the casing 3|, as illustrated in Figure 2. In adjusted position, the bores of the bushings 35 form a continuous passage with the bore of the tube 32. The bushing 35 at the intake end of the casing receives and is joined to the delivery end of the heating coil 23.

The tube 32 is provided with a fin 33 which follows a helical line about the peripheral surface thereof, the convolutions of the fin being spaced apart sufficiently to establish a relatively narrow continuous helical passage, the latter being of a lineal dimension many times that of the central air passage through said tube and is con- I.

tinuous from one end of the tube 32 to the other. The outside diameter of the fin is of a dimension to flt closely to the wall of the bore in the casing 3| so that oil forced into the latter through the port 20 must follow the helical passage to the outlet 20, being brought continuously into contact with the heated surfaces of the helical passage. In practice the heavy fuel may be pumped into the helical passage at approximately F. and the compressed air entering the tube 32 maintained at about 400 to 500 Fahr. As the fuel is advanced through the helical passage its temperature may be increased to about 200 F. or higher if desired, to a point where it is in a highly liquid state. The fuel then flows outwardly through port 20' to an oil atomizer 31. The hot air ,under compression moves rapidly along the tube 32, while the oil in the helix moves relatively ve'ryslowly. The air having given up a quota of its heat content to the 'oil, flows outwardly to an upright connection 33 and thence through a nipple 39 and into conjunction with the oil in the atomizer 3'I- at the point or points of release from pressure. The bulb 23 of the gas regulator valve 21 is secured in an elbow section 40 of the connection 38 and depends into the latter. The air at 300 F. under. five pounds pressure atomization of above 200 F.; so that after taking into account the inherent drop in temperature at this point due to the release of the air from pressure, there will still be sufficient heat remaining in the air to maintain the fuel at a highly liquid consistency, facilitating complete atomization as well as rapid ignition of the fuel.

The operation of my invention The pumps for the air and fuel are set in motion and the air heater ignited. This results in raising the temperature of the compressed air in the heater coil which flows thence rapidly through the heat exchanger and causes the oil in the helical passage to become less viscous as it acquires heat from the hot air stream. Both the air and the fuel are moved in the direction of the atomizer itself. It will be noted that after the courseof heat exchange relation has been passed by the air, its remaining heat content is proportional to temperature in the fittings 3B and 40. The temperature of the air in these fittings acting upon the bulb 29 is the governing factor in automatically maintaining the air stream entering the heat exchanger at the correct temperature to sustain any required heat loss by heat exchange to the fuel, and still retain sufficient heat to prevent viscosity from resisting complete atomization of the fuel at the point of air release from pressure.

Where the use of steam for atomization is preferred to that of air the pipe 22 leading to the heating coil 23 may be placed in communication with a source of steam supply 4| under adequate pressure and the same procedure as above out lined for the use ofcompressed air carried on.

is as follows:- I

In this case the steam to be used for atomization must be superheated, in the coil 23 to a degree which will permit it to supply heat to be used in raising the temperature of the oil in the heat exchanger and still leave a sufficient degree of excess or superheat in the steam after it has passed the heat exchanger to prevent occurrence of condensation atthe' point of its release from pressure. The degree of superheating of the steam will be governed in the same manner and by the same apparatus as is above described for goveming the preheating of compressed air. This apparatus is subject to adjustment for maintenance of any temperature within a considerable range.

Having now described my invention, what 1'.

A claim and desire to secure by Letters Patent is:-

l. In'the art of atomizing liquid fuel by the use of air, the steps of preheating the air, flowing the fuel and the preheated air in heat exchange relation without mixing to reduce the viscosity of the fuel. controlling the .pr'eheating of the air by the temperature of the air beyond the place of heat exchange, discharging the heated fuel as a jet, and discharging the air to atomize the heated fuel.

2. In the art of atomizing liquid fuel by the use of compressed air, the steps of compressing and preheating the air, flowing the fuel and the compressed preheated air in heat exchange relation without mixing to reduce the viscosity of the fuel, controlling the preheating of the air by the temperature of the air beyond the place of heat exchange, discharging the heated fuel as ajet, and discharging the compressed air to atomize the heated fuel. 4 1 THOMAS J. STEPHENS. 

